title: Stabilizing the elusive ortho-quinone/copper(I) oxidation state combination through pi/pi interaction in an isolated complex.
abstract: The heterodinuclear compound [(PhenQ)Cu(dppf)](BF4), PhenQ = 9,10-phenanthrenequinone and dppf = 1,1'-bis(diphenylphosphino)ferrocene, was identified structurally and spectroscopically (NMR, IR, UV-vis) as a copper(I) complex of a completely unreduced ortho-quinone. Crystallographic and DFT calculation results suggest that this stabilization of a hitherto elusive arrangement is partially owed to intramolecular pi/pi interactions phenyl/PhenQ. Intermolecular PhenQ/PhenQ pi stacking is also observed in the crystal. According to DFT calculations, the pi interactions are responsible for the considerably distorted coordination geometry at CuI with one short and one longer Cu-O and Cu-P bond, respectively, and with bond angles at copper ranging from 99 degrees to 133 degrees. Electrochemical reduction proceeds reversibly at low temperatures to yield an EPR spectroscopically characterized semiquinone-copper(I) species.
authors.affiliation: Institut für Anorganische Chemie, Universität Stuttgart, Pfaffenwaldring 55, D-70550 Stuttgart, Germany.
authors.forename: Sayak
authors.initials: S
authors.lastname: Roy
authors.forename: Biprajit
authors.initials: B
authors.lastname: Sarkar
authors.forename: Denis
authors.initials: D
authors.lastname: Bubrin
authors.forename: Mark
authors.initials: M
authors.lastname: Niemeyer
authors.forename: Stanislav
authors.initials: S
authors.lastname: Zális
authors.forename: Goutam Kumar
authors.initials: GK
authors.lastname: Lahiri
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Kaim